//
// Created by 赵路 on 2021/10/12.
//

#include "des.h"

/* 初始置换表IP */
int IP[] = {
        58, 50, 42, 34, 26, 18, 10, 2,
        60, 52, 44, 36, 28, 20, 12, 4,
        62, 54, 46, 38, 30, 22, 14, 6,
        64, 56, 48, 40, 32, 24, 16, 8,
        57, 49, 41, 33, 25, 17, 9, 1,
        59, 51, 43, 35, 27, 19, 11, 3,
        61, 53, 45, 37, 29, 21, 13, 5,
        63, 55, 47, 39, 31, 23, 15, 7
};

/* 初始置换逆表PC-1 */
int IP_1[] = {
        40, 8, 48, 16, 56, 24, 64, 32,
        39, 7, 47, 15, 55, 23, 63, 31,
        38, 6, 46, 14, 54, 22, 62, 30,
        37, 5, 45, 13, 53, 21, 61, 29,
        36, 4, 44, 12, 52, 20, 60, 28,
        35, 3, 43, 11, 51, 19, 59, 27,
        34, 2, 42, 10, 50, 18, 58, 26,
        33, 1, 41, 9, 49, 17, 57, 25
};

/* 密钥置换表PC-1 (64bit to 56bit) */
int PC_1[] = {
        57, 49, 41, 33, 25, 17, 9,
        1, 58, 50, 42, 34, 26, 18,
        10, 2, 59, 51, 43, 35, 27,
        19, 11, 3, 60, 52, 44, 36,
        63, 55, 47, 39, 31, 23, 15,
        7, 62, 54, 46, 38, 30, 22,
        14, 6, 61, 53, 45, 37, 29,
        21, 13, 5, 28, 20, 12, 4
};

/* 循环左移的位数 */
int shiftBits[] = {1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1};

/* 密钥置换表PC-2 (56bit to 48bit) */
int PC_2[] = {
        14, 17, 11, 24, 1, 5,
        3, 28, 15, 6, 21, 10,
        23, 19, 12, 4, 26, 8,
        16, 7, 27, 20, 13, 2,
        41, 52, 31, 37, 47, 55,
        30, 40, 51, 45, 33, 48,
        44, 49, 39, 56, 34, 53,
};

/* 扩展置换E (32bit to 48bit) */
int E[] = {32, 1, 2, 3, 4, 5,
           4, 5, 6, 7, 8, 9,
           8, 9, 10, 11, 12, 13,
           12, 13, 14, 15, 16, 17,
           16, 17, 18, 19, 20, 21,
           20, 21, 22, 23, 24, 25,
           24, 25, 26, 27, 28, 29,
           28, 29, 30, 31, 32, 1
};

/* S盒 (48bit to 32bit)*/
int S_BOX[8][4][16] = {
        {
                {14, 4,  13, 1,  2,  15, 11, 8,  3,  10, 6,  12, 5,  9,  0,  7},
                {0,  15, 7,  4,  14, 2,  13, 1,  10, 6, 12, 11, 9,  5,  3,  8},
                {4,  1,  14, 8,  13, 6,  2,  11, 15, 12, 9,  7,  3,  10, 5,  0},
                {15, 12, 8,  2,  4,  9,  1,  7,  5,  11, 3,  14, 10, 0, 6,  13}
        },
        {
                {15, 1,  8,  14, 6,  11, 3,  4,  9,  7,  2,  13, 12, 0,  5,  10},
                {3,  13, 4,  7,  15, 2,  8,  14, 12, 0, 1,  10, 6,  9,  11, 5},
                {0,  14, 7,  11, 10, 4,  13, 1,  5,  8,  12, 6,  9,  3,  2,  15},
                {13, 8,  10, 1,  3,  15, 4,  2,  11, 6,  7,  12, 0,  5, 14, 9}
        },
        {
                {10, 0,  9,  14, 6,  3,  15, 5,  1,  13, 12, 7,  11, 4,  2,  8},
                {13, 7,  0,  9,  3,  4,  6,  10, 2,  8, 5,  14, 12, 11, 15, 1},
                {13, 6,  4,  9,  8,  15, 3,  0,  11, 1,  2,  12, 5,  10, 14, 7},
                {1,  10, 13, 0,  6,  9,  8,  7,  4,  15, 14, 3,  11, 5, 2,  12}
        },
        {
                {7,  13, 14, 3,  0,  6,  9,  10, 1,  2,  8,  5,  11, 12, 4,  15},
                {13, 8,  11, 5,  6,  15, 0,  3,  4,  7, 2,  12, 1,  10, 14, 9},
                {10, 6,  9,  0,  12, 11, 7,  13, 15, 1,  3,  14, 5,  2,  8,  4},
                {3,  15, 0,  6,  10, 1,  13, 8,  9,  4,  5,  11, 12, 7, 2,  14}
        },
        {
                {2,  12, 4,  1,  7,  10, 11, 6,  8,  5,  3,  15, 13, 0,  14, 9},
                {14, 11, 2,  12, 4,  7,  13, 1,  5,  0, 15, 10, 3,  9,  8,  6},
                {4,  2,  1,  11, 10, 13, 7,  8,  15, 9,  12, 5,  6,  3,  0,  14},
                {11, 8,  12, 7,  1,  14, 2,  13, 6,  15, 0,  9,  10, 4, 5,  3}
        },
        {
                {12, 1,  10, 15, 9,  2,  6,  8,  0,  13, 3,  4,  14, 7,  5,  11},
                {10, 15, 4,  2,  7,  12, 9,  5,  6,  1, 13, 14, 0,  11, 3,  8},
                {9,  14, 15, 5,  2,  8,  12, 3,  7,  0,  4,  10, 1,  13, 11, 6},
                {4,  3,  2,  12, 9,  5,  15, 10, 11, 14, 1,  7,  6,  0, 8,  13}
        },
        {
                {4,  11, 2,  14, 15, 0,  8,  13, 3,  12, 9,  7,  5,  10, 6,  1},
                {13, 0,  11, 7,  4,  9,  1,  10, 14, 3, 5,  12, 2,  15, 8,  6},
                {1,  4,  11, 13, 12, 3,  7,  14, 10, 15, 6,  8,  0,  5,  9,  2},
                {6,  11, 13, 8,  1,  4,  10, 7,  9,  5,  0,  15, 14, 2, 3,  12}
        },
        {
                {13, 2,  8,  4,  6,  15, 11, 1,  10, 9,  3,  14, 5,  0,  12, 7},
                {1,  15, 13, 8,  10, 3,  7,  4,  12, 5, 6,  11, 0,  14, 9,  2},
                {7,  11, 4,  1,  9,  12, 14, 2,  0,  6,  10, 13, 15, 3,  5,  8},
                {2,  1,  14, 7,  4,  10, 8,  13, 15, 12, 9,  0,  3,  5, 6,  11}
        }
};

/* P置换 (32bit to 32bit)*/
int P[] = {
        16, 7, 20, 21,
        29, 12, 28, 17,
        1, 15, 23, 26,
        5, 18, 31, 10,
        2, 8, 24, 14,
        32, 27, 3, 9,
        19, 13, 30, 6,
        22, 11, 4, 25
};

bitset<64> charToBitset(const char s[8]) {
    bitset<64> bits;
    for (int i = 0; i < 8; ++i) {
        for (int j = 0; j < 8; ++j) {
            bits[i * 8 + j] = ((s[i] >> j) & 1);
        }
    }
    return bits;
}

bitset<28> leftShift(bitset<28> k, int shift) {
    bitset<28> tmp = k;
    for (int i = 27; i >= 0; --i) {
        if (i - shift < 0) {
            k[i] = tmp[i - shift + 28];
        } else {
            k[i] = tmp[i - shift];
        }
    }
    return k;
}

void generateKeys() {
    bitset<56> realKey;
    bitset<28> left;
    bitset<28> right;
    bitset<48> compressKey;
    // 去掉奇偶标记位，并进行PC-1置换
    for (int i = 0; i < 56; ++i) {
        realKey[55 - i] = Key[64 - PC_1[i]];
    }
    // 生成子密钥，保存在subKeys[16]中
    for (int round = 0; round < 16; ++round) {
        // 分割前28位与后28位
        for (int i = 28; i < 56; ++i) {
            left[i - 28] = realKey[i];
        }
        for (int i = 0; i < 28; ++i) {
            right[i] = realKey[i];
        }
        // 循环左移
        left = leftShift(left, shiftBits[round]);
        right = leftShift(right, shiftBits[round]);
        // 拼接
        for (int i = 28; i < 56; ++i) {
            realKey[i] = left[i - 28];
        }
        for (int i = 0; i < 28; ++i) {
            realKey[i] = right[i];
        }
        // PC-2置换
        for (int i = 0; i < 48; ++i) {
            compressKey[47 - i] = realKey[56 - PC_2[i]];
        }
        subKey[round] = compressKey;
    }
}

bitset<32> f(bitset<32> R, bitset<48> k) {
    bitset<48> expandR;
    // 扩展置换
    for (int i = 0; i < 48; ++i) {
        expandR[47 - i] = R[32 - E[i]];
    }
    // 异或
    expandR = expandR ^ k;
    // S盒
    bitset<32> output;
    int x = 0;
    for (int i = 0; i < 48; i = i + 6) {
        int row = expandR[47 - i] * 2 + expandR[47 - i - 5];
        int col = expandR[47 - i - 1] * 8 + expandR[47 - i - 2] * 4 + expandR[47 - i - 3] * 2 + expandR[47 - i - 4];
        int num = S_BOX[i / 6][row][col];
        bitset<4> binary(num);
        output[31 - x] = binary[3];
        output[31 - x - 1] = binary[2];
        output[31 - x - 2] = binary[1];
        output[31 - x - 3] = binary[0];
        x += 4;
    }
    // P置换
    bitset<32> tmp = output;
    for (int i = 0; i < 32; ++i) {
        output[31 - i] = tmp[32 - P[i]];
    }
    return output;
}

bitset<64> encrypt(bitset<64> &plain) {
    bitset<64> cipher;
    bitset<64> currentBits;
    bitset<32> left;
    bitset<32> right;
    bitset<32> newLeft;
    // 初始置换IP
    for (int i = 0; i < 64; ++i) {
        currentBits[63 - i] = plain[64 - IP[i]];
    }
    // Li 和 Ri
    for (int i = 32; i < 64; ++i) {
        left[i - 32] = currentBits[i];
    }
    for (int i = 0; i < 32; ++i) {
        right[i] = currentBits[i];
    }
    // 16轮迭代
    for (auto &round : subKey) {
        newLeft = right;
        right = left ^ f(right, round);
        left = newLeft;
    }
    // 合并L16和R16为L16R16
    for (int i = 0; i < 32; ++i) {
        cipher[i] = left[i];
    }
    for (int i = 32; i < 64; ++i) {
        cipher[i] = right[i - 32];
    }
    // 初始逆置换IP-1
    currentBits = cipher;
    for (int i = 0; i < 64; ++i) {
        cipher[63 - i] = currentBits[64 - IP_1[i]];
    }
    return cipher;
}

bitset<64> decrypt(bitset<64> &cipher) {
    bitset<64> plain;
    bitset<64> currentBits;
    bitset<32> left;
    bitset<32> right;
    bitset<32> newLeft;
    // 初始置换IP
    for (int i = 0; i < 64; ++i) {
        currentBits[63 - i] = cipher[64 - IP[i]];
    }
    // Li 和 Ri
    for (int i = 32; i < 64; ++i) {
        left[i - 32] = currentBits[i];
    }
    for (int i = 0; i < 32; ++i) {
        right[i] = currentBits[i];
    }
    // 16轮迭代
    for (int round = 0; round < 16; ++round) {
        newLeft = right;
        right = left ^ f(right, subKey[15 - round]);
        left = newLeft;
    }
    // 合并L16和R16为R16L16
    for (int i = 0; i < 32; ++i)
        plain[i] = left[i];
    for (int i = 32; i < 64; ++i)
        plain[i] = right[i - 32];
    // 初始逆置换IP-1
    currentBits = plain;
    for (int i = 0; i < 64; ++i) {
        plain[63 - i] = currentBits[64 - IP_1[i]];
    }
    return plain;
}
